BLAS/SRC/dsyr2k.f(3)

NAME
BLAS/SRC/dsyr2k.f

SYNOPSIS

  Functions/Subroutines
subroutine dsyr2k (uplo, trans, n, k, alpha, a, lda, b, ldb, beta, c, ldc)
DSYR2K

Function/Subroutine Documentation

  subroutine dsyr2k (character uplo, character trans, integer n, integer k, double precision alpha, double precision, dimension(lda,*) a, integer lda, double precision, dimension(ldb,*) b, integer ldb, double precision beta, double precision, dimension(ldc,*) c, integer ldc)

DSYR2K

Purpose:

    !>
    !> DSYR2K  performs one of the symmetric rank 2k operations
    !>
    !>    C := alpha*A*B**T + alpha*B*A**T + beta*C,
    !>
    !> or
    !>
    !>    C := alpha*A**T*B + alpha*B**T*A + beta*C,
    !>
    !> where  alpha and beta  are scalars, C is an  n by n  symmetric matrix
    !> and  A and B  are  n by k  matrices  in the  first  case  and  k by n
    !> matrices in the second case.
    !>

Parameters
    UPLO

    !>          UPLO is CHARACTER*1
    !>           On  entry,   UPLO  specifies  whether  the  upper  or  lower
    !>           triangular  part  of the  array  C  is to be  referenced  as
    !>           follows:
    !>
    !>              UPLO = 'U' or 'u'   Only the  upper triangular part of  C
    !>                                  is to be referenced.
    !>
    !>              UPLO = 'L' or 'l'   Only the  lower triangular part of  C
    !>                                  is to be referenced.
    !>

    TRANS

    !>          TRANS is CHARACTER*1
    !>           On entry,  TRANS  specifies the operation to be performed as
    !>           follows:
    !>
    !>              TRANS = 'N' or 'n'   C := alpha*A*B**T + alpha*B*A**T +
    !>                                        beta*C.
    !>
    !>              TRANS = 'T' or 't'   C := alpha*A**T*B + alpha*B**T*A +
    !>                                        beta*C.
    !>
    !>              TRANS = 'C' or 'c'   C := alpha*A**T*B + alpha*B**T*A +
    !>                                        beta*C.
    !>

    N

    !>          N is INTEGER
    !>           On entry,  N specifies the order of the matrix C.  N must be
    !>           at least zero.
    !>

    K

    !>          K is INTEGER
    !>           On entry with  TRANS = 'N' or 'n',  K  specifies  the number
    !>           of  columns  of the  matrices  A and B,  and on  entry  with
    !>           TRANS = 'T' or 't' or 'C' or 'c',  K  specifies  the  number
    !>           of rows of the matrices  A and B.  K must be at least  zero.
    !>

    ALPHA

    !>          ALPHA is DOUBLE PRECISION.
    !>           On entry, ALPHA specifies the scalar alpha.
    !>

    A

    !>          A is DOUBLE PRECISION array, dimension ( LDA, ka ), where ka is
    !>           k  when  TRANS = 'N' or 'n',  and is  n  otherwise.
    !>           Before entry with  TRANS = 'N' or 'n',  the  leading  n by k
    !>           part of the array  A  must contain the matrix  A,  otherwise
    !>           the leading  k by n  part of the array  A  must contain  the
    !>           matrix A.
    !>

    LDA

    !>          LDA is INTEGER
    !>           On entry, LDA specifies the first dimension of A as declared
    !>           in  the  calling  (sub)  program.   When  TRANS = 'N' or 'n'
    !>           then  LDA must be at least  max( 1, n ), otherwise  LDA must
    !>           be at least  max( 1, k ).
    !>

    B

    !>          B is DOUBLE PRECISION array, dimension ( LDB, kb ), where kb is
    !>           k  when  TRANS = 'N' or 'n',  and is  n  otherwise.
    !>           Before entry with  TRANS = 'N' or 'n',  the  leading  n by k
    !>           part of the array  B  must contain the matrix  B,  otherwise
    !>           the leading  k by n  part of the array  B  must contain  the
    !>           matrix B.
    !>

    LDB

    !>          LDB is INTEGER
    !>           On entry, LDB specifies the first dimension of B as declared
    !>           in  the  calling  (sub)  program.   When  TRANS = 'N' or 'n'
    !>           then  LDB must be at least  max( 1, n ), otherwise  LDB must
    !>           be at least  max( 1, k ).
    !>

    BETA

    !>          BETA is DOUBLE PRECISION.
    !>           On entry, BETA specifies the scalar beta.
    !>

    C

    !>          C is DOUBLE PRECISION array, dimension ( LDC, N )
    !>           Before entry  with  UPLO = 'U' or 'u',  the leading  n by n
    !>           upper triangular part of the array C must contain the upper
    !>           triangular part  of the  symmetric matrix  and the strictly
    !>           lower triangular part of C is not referenced.  On exit, the
    !>           upper triangular part of the array  C is overwritten by the
    !>           upper triangular part of the updated matrix.
    !>           Before entry  with  UPLO = 'L' or 'l',  the leading  n by n
    !>           lower triangular part of the array C must contain the lower
    !>           triangular part  of the  symmetric matrix  and the strictly
    !>           upper triangular part of C is not referenced.  On exit, the
    !>           lower triangular part of the array  C is overwritten by the
    !>           lower triangular part of the updated matrix.
    !>

    LDC

    !>          LDC is INTEGER
    !>           On entry, LDC specifies the first dimension of C as declared
    !>           in  the  calling  (sub)  program.   LDC  must  be  at  least
    !>           max( 1, n ).
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Further Details:

    !>
    !>  Level 3 Blas routine.
    !>
    !>
    !>  -- Written on 8-February-1989.
    !>     Jack Dongarra, Argonne National Laboratory.
    !>     Iain Duff, AERE Harwell.
    !>     Jeremy Du Croz, Numerical Algorithms Group Ltd.
    !>     Sven Hammarling, Numerical Algorithms Group Ltd.
    !>

Definition at line 191 of file dsyr2k.f.

Author

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